AI Coding & CSE Fundamentals

Unlock a world of free educational content, expert-led courses, and skill-building resources — all designed to empower you, grow your knowledge, and help you get certified with confidence. 💡 Tip for Success: Focus on one course at a time. Learn deeply, complete it fully, and apply what you learn. Mastery comes step by step! ⭐ Join & begin your journey today! https://t.me/skills_stream_free_courses

Leetcode 283: https://leetcode.com/problems/move-zeroes/

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        if (nums.size() < 2) {
            return;
        }
        
        int leftIdx = 0, rightIdx = 1;
        
        while (rightIdx < nums.size()) {
            if (nums[leftIdx] != 0) {
                leftIdx++;
                rightIdx++;
            } 
            else if (nums[rightIdx] == 0) {
                rightIdx++;
            } 
            else {
                swap(nums[leftIdx], nums[rightIdx]);
            }
        }
    }
};

Leetcode 66: https://leetcode.com/problems/plus-one/

class Solution {
public:
    std::vector<int> plusOne(std::vector<int>& digits) {
        int currentIndex = digits.size() - 1;
        
        while (digits[currentIndex] == 9) {
            if (currentIndex == 0) {
                std::vector<int> resultArr(digits.size() + 1, 0);
                resultArr[0] = 1;
                return resultArr;
            }
            digits[currentIndex] = 0;
            currentIndex--;
        }

        digits[currentIndex]++;
        return digits;
    }
};

Leetcode 350: https://leetcode.com/problems/intersection-of-two-arrays-ii/

class Solution {
public:
    std::vector<int> intersect(std::vector<int>& nums1, std::vector<int>& nums2) {
        std::unordered_map<int, int> numsMap;
        std::vector<int> intersectedNums;

        for (int num : nums1) {
            numsMap[num]++;
        }

        for (int num : nums2) {
            if (numsMap.find(num) != numsMap.end() && numsMap[num] > 0) {
                intersectedNums.push_back(num);
                numsMap[num]--;
                if (numsMap[num] == 0) {
                    numsMap.erase(num);
                }
            }
        }

        return intersectedNums;
    }
};

Leetcode 136: https://leetcode.com/problems/single-number/

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int finder = 0;
        for(int i = 0; i < nums.size(); i++) {
            finder = finder ^ nums[i];
        }
        return finder;
    }
};

Leetcode 217: https://leetcode.com/problems/contains-duplicate/description/

#include <vector>
#include <algorithm>

class Solution {
public:
    bool containsDuplicate(std::vector<int>& nums) {
        std::sort(nums.begin(), nums.end());
        for (size_t i = 0; i < nums.size() - 1; i++) {
            if (nums[i] == nums[i + 1]) {
                return true;
            }
        }
        return false;
    }
};

Leetcode 189: https://leetcode.com/problems/rotate-array/

#include <vector>
#include <iostream>

class Solution {
public:
    void rotate(std::vector<int>& nums, int k) {
        k = k % nums.size();
        // Reversing the whole array
        reverseNumsArr(nums, 0, nums.size());
        // Reversing first k elements
        reverseNumsArr(nums, 0, k);
        // Reversing remaining elements
        reverseNumsArr(nums, k, nums.size());
    }

private:
    void reverseNumsArr(std::vector<int>& nums, int start, int end) {
        end--; // Adjusting end to be the last index
        while (start < end) {
            std::swap(nums[start], nums[end]);
            start++;
            end--;
        }
    }
};

Leetcode 122: https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int maxProfit = 0;
        for(int i = 0; i < prices.size() - 1; i++) {
            if(prices[i] < prices[i + 1]) {
                int diff = prices[i + 1] - prices[i];
                maxProfit += diff;
            }
        }
        return maxProfit;
    }
};

Leetcode 26: https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        int lastUniqueElementIdx = 0;

        for (int i = 1; i < nums.size(); i++) {
            if (nums[lastUniqueElementIdx] != nums[i]) {
                nums[lastUniqueElementIdx + 1] = nums[i];
                lastUniqueElementIdx++;
            }
        }
        return lastUniqueElementIdx + 1;
    }
};

Amazing free courses are out guys checkout 👇👇👇 https://t.me/udemy_course_4u

Program: Searching in a 2D array.

#include <iostream>
using namespace std;

int* search(int arr[][3], int rows, int cols, int target) {
    static int result[2]; 
    result[0] = -1;
    result[1] = -1;

    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            if (arr[i][j] == target) {
                result[0] = i;
                result[1] = j;
                return result; 
            }
        }
    }
    return result; 
}

int main() {
    int arr[3][3] = {
        {20, 45, 10},
        {32, 26, 22},
        {47, 98, 37}
    };

    int target;
    cout << "Enter target element: ";
    cin >> target;

    int* result = search(arr, 3, 3, target);
    
    if (result[0] != -1) {
        cout << "Element found at index (" << result[0] << "," << result[1] << ")" << endl;
    } else {
        cout << "Element not found" << endl;
    }

    return 0;
}

#linearsearch

Program: Finding maximum element from an array.

#include <iostream>
using namespace std;

int findMax(int arr[], int size) {
    int max = arr[0];
    for (int i = 1; i < size; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    return max;
}

int main() {
    int arr[] = {12, 32, 23, 11, 39};
    int size = sizeof(arr) / sizeof(arr[0]);
    int maxNumber = findMax(arr, size);
    cout << "Maximum number in array: " << maxNumber << endl;
    return 0;
}

Program: Finding minimum element in an array.

#include <iostream>
using namespace std;

int findMin(int arr[], int size) {
    int min = arr[0];
    for (int i = 1; i < size; i++) {
        if (arr[i] < min) {
            min = arr[i];
        }
    }
    return min;
}

int main() {
    int arr[] = {12, 32, 23, 11, 39};
    int size = sizeof(arr) / sizeof(arr[0]);
    int minNumber = findMin(arr, size);
    cout << "Minimum number in array: " << minNumber << endl;
    return 0;
}

Program: Searching for a character in specified range.

#include <iostream>
#include <string>

using namespace std;

int searchInStr(const string &str, char ch, int start, int end) {
    for (int i = start; i <= end; i++) {
        if (str[i] == ch) {
            return i;
        }
    }
    return -1;
}

int main() {
    string str = "Java Programming";
    char ch;
    int start, end;
    
    cout << "Enter character to search: ";
    cin >> ch;
    
    cout << "Enter the range,\n";
    cout << "Enter the start index: ";
    cin >> start;
    cout << "Enter the end index: ";
    cin >> end;
    
    int res = searchInStr(str, ch, start, end);
    
    if (res == -1) {
        cout << "Character not found in the specified range" << endl;
    } else {
        cout << "Character is at index " << res << endl;
    }
    
    return 0;
}

Program: Searching for first occurrence of a character in a string.

#include <iostream>
using namespace std;

int searchInStr(string str, char ch) {
    for (int i = 0; i < str.length(); i++) {
        if (str[i] == ch) {
            return i;
        }
    }
    return -1;
}

int main() {
    string str = "Java Programming";
    char ch;
    cout << "Enter character to search: ";
    cin >> ch;
    int res = searchInStr(str, ch);
    if (res == -1) {
        cout << "Character not found in the String" << endl;
    } else {
        cout << "Character is at index " << res << endl;
    }
    return 0;
}

Program: Reversing of an Array.

#include <iostream>
#include <vector>
using namespace std;

void reverseArray(vector<int>& arr) {
    int n = arr.size();
    for (int i = 0; i < n / 2; i++) {
        swap(arr[i], arr[n - 1 - i]);
    }
}

int main() {
    vector<int> arr = {1, 2, 3, 4, 5, 6};
    reverseArray(arr);

    for (size_t i = 0; i < arr.size(); i++) {
        cout << arr[i] << " ";
    }
    cout << endl;

    return 0;
}

Program : Finding Maximum element in an Array.

#include <iostream>
using namespace std;

int findMax(int arr[], int size) {
    int maxElem = arr[0];
    for(int i = 1; i < size; i++) {
        if(maxElem < arr[i]) {
            maxElem = arr[i];
        }
    }
    return maxElem;
}

int main() {
    int arr[] = {10, 5, 1, 3, 6};
    int size = sizeof(arr) / sizeof(arr[0]);
    int maxElem = findMax(arr, size);
    cout << "Maximum Element : " << maxElem << endl;
    return 0;
}

🚨🚨🚨Free Udemy Courses Guys join this channel if you want any courses like c,cpp, java and other technical stuff. stay active in channel by unmuting it and enroll to the course as soon as they are posted . It's really worth guys don't miss 👇👇👇 https://t.me/udemy_course_4u

Program : Armstrong or Not

#include <iostream>
#include <cmath> 
using namespace std;

bool isArmstrong(int num) {
    int originalNum = num, sum = 0, digits = to_string(num).length();
    while (num > 0) {
        int rem = num % 10;
        sum += pow(rem, digits); 
        num /= 10;
    }
    return originalNum == sum;
}

int main() {
    int num;
    cout << "Enter any number: ";
    cin >> num;

    if (isArmstrong(num)) {
        cout << num << " is an Armstrong number." << endl;
    } else {
        cout << num << " is not an Armstrong number." << endl;
    }
    return 0;
}

Program : Prime or Not

#include <iostream>
using namespace std;

bool isPrime(int num) {
    if (num < 2) {
        return false;
    }
    for (int i = 2; i * i <= num; i++) {
        if (num % i == 0) {
            return false;
        }
    }
    return true;
}

int main() {
    int num;
    cout << "Enter any number: ";
    cin >> num;
    if (isPrime(num)) {
        cout << num << " is a prime number" << endl;
    } else {
        cout << num << " is not a prime number" << endl;
    }
    return 0;
}